Generally, in a mount device for an outboard motor disposed between an outboard motor body and an attachment device through which the outboard motor body is attached to a hull, a mount unit including an upper mount unit and a lower mount unit which are arranged in an upper portion and a lower portion of the outboard motor body, and vibration of an engine is prevented from transmitting to the hull by providing an elastic body, such as rubber material, in the mount unit.
In order to improve vibration prevention performance of such mount device, it is necessary to set a spring constant of the elastic body to be small to thereby prevent vibration particularly during low-speed rotation of the engine from transmitting to the hull. However, when a large load is applied to the outboard motor body as in a case in which a thrust of the outboard motor body rapidly changes, only the elastic body may not be able to prevent interference between a member on the outboard motor body side (e.g., an engine holder) and a member on the attachment device side (e.g., a swivel bracket). Patent Document 1 discloses a mount device for an outboard motor that solves the above-mentioned problem.
The mount device for an outboard motor disclosed in Patent Document 1 includes, as shown in FIG. 10, a first upper mount 101 that performs a function to prevent transmission of vibration, a second upper mount 102 that performs a function to restrict displacement of an outboard motor body during forward movement of a hull, a third upper mount 103 that performs a function to restrict displacement of the outboard motor body during backward movement of the hull, a fourth upper mount 104 that performs a function to restrict displacement in right-left and up-down directions of the outboard motor body, and a fifth upper mount 105 that performs a function to restrict rotational displacement in a yaw direction (a rotational direction about a gravity center position O within a horizontal plane of the outboard motor body) of the outboard motor body.